Around the world firefighters risk their lives by blindly entering smoke-filled structures hundreds of times a day. To avoid the choking smoke which obstructs their vision they often crawl along the floor. This helps them evade the intense heat as well as thick smoke. Innovation has provided this profession with many tools to deal with these harsh environments—items such as protective garments, oxygen masks, helmets and flashlights. These tools provide some aid in their endeavor to save lives and property.
However, there are problems with the existing technologies. Many people believe that the greatest danger to a fireperson is the risk of the fire itself. While it is true that being burned is a hazard, smoke claims more lives than the flames. In addition to smoke inhalation itself, firefighters become disorientated and may be unable to find egress or be rescued due to thick smoke in, e.g., burning buildings.
When attempting to navigate a smoke-filled structure the best flashlight on the market today is not able to provide much help. This is because flashlights use white or incoherent light. This full spectrum light illuminates the smoke molecules which reflect the light, thereby reducing penetration of the flashlight's beam through the smoke. Several lighting innovations have been introduced in recent years. For example, a so-called “rope” light has been introduced which the firefighter must pull along the floor when entering a burning structure in an attempt to mark his path to egress and to indicate to others where he/she has been in the burning structure. There are various problems with this solution to marking and illuminating paths within burning, smoke-filled structures. For example, the rope light will have a limited length, it may get tangled or caught on objects within the structure and may add significantly to the weight carried by a firefighter, depending upon the length of rope provided.
More recently, an emergency lighting device for firefighters has been described in U.S. Pat. No. 6,864,799, hereafter referred to as the “'799 patent”. The '799 patent describes a safety device for firefighters usable to mark a viable exit for a building. The safety device includes an audible sounder and a number of laser diodes in a housing with lenses that create panes or sheets of light. The housing of the device can have prongs that allow the device to pierce drywall to mount it near a door or window, as well as an adhesive or cement for mounting on other vertical surfaces. The housing also has a tapered wedge shape and can wedge a door in an open position. There can be, for example, four laser diodes oriented at various angles within the device described by the '799 patent.
Although the device described in the '799 patent does use coherent light, rather than the incoherent light supplied by flashlights, it suffers from a number of potential drawbacks associated with its usage in certain real-life firefighting situations. For example, the creation of panes or sheets of light by the device described in the '799 patent will provide poor penetration of the smoke in burning structures, making it hard to see by firefighters seeking egress. Additionally, the use of a toggle switch on the side of the device to activate/deactivate the device will likely be problematic to operate for a firefighter wearing bulky, fire resistant gloves. Additionally, such a toggle switch may be easily triggered inadvertently, potentially rendering the device unusable if the battery is drained.
Accordingly, it would be desirable to develop emergency lighting devices for firefighters which overcome these and other drawbacks associated with existing devices and methods.